Please describe the problem:
Using the implements interface method to check if alsasrc implements an interface other than Mixer results in an Error and program termination. This is despite the fact that alsasrc *does* support the PropertyProbe interface.

Using the same method to check if alsamixer supports an interface except Mixer results in a critical assertion and a return value of false, even though alsamixer also supports the PropertyProbe interface.

Steps to reproduce:
In a python shell:
>>> import gst
>>> aa = gst.element_factory_make("alsasrc")
>>> aa.implements_interface(gst.interfaces.PropertyProbe)
**
** ERROR:(gstalsasrc.c:162):gst_alsasrc_interface_supported: assertion failed: (interface_type == GST_TYPE_MIXER)
Aborted

In a python shell:
>>> import gst
>>> am = gst.element_factory_make("alsamixer")
>>> am.implements_interface(gst.interfaces.PropertyProbe)

** (.:26954): CRITICAL **: file gstalsamixerelement.c: line 69 (gst_alsa_mixer_element_interface_supported): should not be reached
False
>>>



Actual results:


Expected results:
I expect both queries for gst.interfaces.PropertyProbe to return True.

Does this happen every time?


Other information: